1. Field of the Invention
The present invention relates to the hydrogenation of acetophenone (herein "ACP") to alpha-methyl benzyl alcohol (herein "MBA") using a supported palladium catalyst, wherein an ethylbenzene and/or MBA solvent is used and catalyst activity is maintained by the incorporation of small amounts of water in the hydrogenation reaction mixture.
2. Description of the Prior Art
Methods have previously been known for the hydrogenation of ACP to MBA. U.S. Pat. Nos. 3,927,120 and 3,927,121 relate to this reaction using copper type catalysts. U.S. Pat. No. 4,208,539 also shows the hydrogenation of ACP to MBA, a barium-copper chromite-zinc catalyst is used.
Hydrogenation conditions tend to be somewhat severe where copper type catalysts are used, and efforts have been made to develop systems which are effective at milder hydrogenation conditions.
Britner, et al., J. Org. Chem., Vol. 24, pages 1855-1857 (1959) show hydrogenation of ACP to MBA using a palladium on carbon catalyst as do Freifelder, et al., J. Pharm. Sciences, Vol. 53, page 967 (1964), Rylander, et al., Engelhard Industries, Inc., Tech. Bull. 8(4), pages 148-153 (1968) and Baltzly, J. Org. Chem., Vol. 41, No. 6, pages 920-936 (1976). Zavgorodnii, et al., React. Kinet. Catal. Lett., Vol. 11, No. 1, pages 31-34 (1979) also show ACP hydrogenation over various supported catalysts.
Although ACP hydrogenation to MBA over supported palladium catalysts has been reported, we have found that a severe disadvantage of such systems is the tendency for the systems to rapidly lose activity.